| 摘要 |
PURPOSE:To focus each alignment sensor individually, accurately and quickly when the positions of a plurality of alignment marks are detected optically by means of a plurality of systems of alignment sensors. CONSTITUTION:A light reflected on a mark of FIA system put on a wafer is received at an FIA system detecting section 51 through an objective lens 23 and the like and then the X or Y coordinate of the wafer mark is measured. In case of an LIA system wafer mark, a laser beam is projected from an LIA system detecting section 34 through the objective lens 23 or the like onto the wafer. For the purpose of focusing, a plurality of patterns in a slit plate 37 are projected through the objective lens 23 and the like onto each water mark. The image is then projected again onto a line sensor 39 through a shade 38 and the like and the focus position of each wafer mark is detected based on the lateral shift of the image projected again. |
